Three-dimensional modeling apparatus and ejection unit

ABSTRACT

Provided is a three-dimensional modeling apparatus including: a drive motor; a screw that has a groove formation surface with a groove formed therein and that is rotated by the drive motor; a barrel that has a facing surface facing the groove formation surface and having a communication hole at the center thereof and a heater; and a nozzle that ejects a modeling material supplied from the communication hole, in which0.03≤(Ss/Ls)/(Sn/Ln)≤5.00  (1)where Ss is an average sectional area that is an arithmetic mean between a maximum sectional area and a minimum sectional area of the groove, Ls is a length of the groove, Sn is a sectional area of the nozzle, and Ln is a length of the nozzle.

The present application is based on, and claims priority from, JPApplication Serial Number 2018-180016, filed Sep. 26, 2018, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a three-dimensional modeling apparatusand an ejection unit.

2. Related Art

For example, JP-A-2010-241016 discloses a plasticization deviceincluding a rotor with a spiral groove formed in an end surface thereofand a barrel that faces the end surface of the rotor in which the spiralgroove is formed and that has a communication hole formed at the centerthereof.

In a case in which a nozzle with a small diameter is used for modeling athree-dimensional modeled article with dimensional precision in athree-dimensional modeling apparatus that melts a material using aplasticization device as described above and ejecting the moltenmaterial from the nozzle, the amount of ejection decreases, and amodeling speed thus decreases. In this regard, the inventors of thepresent application discovered that there was a room for enhancing theamount of ejection by appropriately setting the dimension of the nozzleand the dimension of the spiral groove as a result of intensive studies.

SUMMARY

An advantage of some aspects of the present disclosure is to provide athree-dimensional modeling apparatus with an improved amount of ejectionfrom a nozzle.

According to an aspect of the present disclosure, a three-dimensionalmodeling apparatus is provided. The three-dimensional modeling apparatusincludes: a drive motor; a screw that has a groove formation surfacewith a groove formed therein and that is rotated by the drive motor; abarrel that has a facing surface facing the groove formation surface andhaving a communication hole at the center thereof and a heater; and anozzle that ejects a modeling material supplied from the communicationhole, in which0.03≤(Ss/Ls)/(Sn/Ln)≤5.00  (1)

where Ss is an average sectional area that is an arithmetic mean betweena maximum sectional area and a minimum sectional area of the groove, Lsis a length of the groove, Sn is a sectional area of the nozzle, and Lnis a length of the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram illustrating an outline configurationof a three-dimensional modeling apparatus according to a firstembodiment.

FIG. 2 is a perspective view illustrating a configuration of a flatscrew according to the first embodiment.

FIG. 3 is a bottom view illustrating a configuration of a grooveformation surface according to the first embodiment.

FIG. 4 is a sectional view of the flat screw taken along the line IV-IVaccording to the first embodiment.

FIG. 5 is a sectional view of the flat screw taken along the line V-Vaccording to the first embodiment.

FIG. 6 is a top view illustrating a configuration of a screw facingsurface of a barrel according to the first embodiment.

FIG. 7 is an explanatory diagram of a rectangular tube model with asimplified groove in the flat screw.

FIG. 8 is a first explanatory diagram illustrating a flow of a modelingmaterial in the rectangular tube.

FIG. 9 is a second explanatory diagram illustrating a flow of themodeling material in the rectangular tube.

FIG. 10 is a third explanatory diagram illustrating a flow of themodeling material in the rectangular tube.

FIG. 11 is a first graph illustrating a relationship between an S/Lratio and an amount of ejection.

FIG. 12 is a first table illustrating a relationship between the S/Lratio and the amount of ejection.

FIG. 13 is a second graph illustrating a relationship between the S/Lratio and the amount of ejection.

FIG. 14 is a second table illustrating a relationship between the S/Lratio and the amount of ejection.

FIG. 15 is a third graph illustrating a relationship between the S/Lratio and the amount of ejection.

FIG. 16 is a third table illustrating a relationship between the S/Lratio and the amount of ejection.

FIG. 17 is a fourth graph illustrating a relationship between the S/LRratio and the amount of ejection.

FIG. 18 is a fourth table illustrating a relationship between the S/Lratio and the amount of ejection.

FIG. 19 is a graph illustrating shear velocity dependency of viscosityof ABS resin.

FIG. 20 is a graph illustrating shear velocity dependency of viscosityof polypropylene.

FIG. 21 is a bottom view illustrating a configuration of a grooveformation surface according to a second embodiment.

FIG. 22 is a graph illustrating a relationship between an S/L ratio andan amount of ejection when a plurality of grooves are provided.

FIG. 23 is a table illustrating a relationship between an S/L ratio andan amount of ejection when two grooves are provided.

FIG. 24 is a table illustrating a relationship between an S/L ratio andan amount of ejection when three grooves are provided.

FIG. 25 is an explanatory diagram illustrating an outline configurationof an injection molding apparatus according to another embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS A. First Embodiment

FIG. 1 is an explanatory diagram illustrating an outline configurationof a three-dimensional modeling apparatus 100 according to a firstembodiment. In FIG. 1, arrows along X, Y, and Z directions thatperpendicularly intersect each other are illustrated. The X directionand the Y direction are directions along a horizontal direction, and theZ direction is a direction along a vertical direction. In the otherdiagrams, arrows along the X, Y, and Z directions are appropriatelyillustrated. The X, Y, and Z directions in FIG. 1 and the X, Y, and Zdirections in the other diagrams represent the same directions.

The three-dimensional modeling apparatus 100 according to the embodimentincludes an ejection unit 200 that has a nozzle 60 and a plasticizationdevice 90, a modeling table 310, a moving mechanism 320, and a controlunit 500. In the three-dimensional modeling apparatus 100 according tothe embodiment, a modeling material plasticized by the plasticizationdevice 90 is supplied to the nozzle 60, and the modeling materialejected from the nozzle 60 is stacked on the modeling table 310 undercontrol provided by the control unit 500, thereby forming athree-dimensional modeled article. Note that the modeling material mayalso be referred to as a molten material.

The moving mechanism 320 changes relative positions of the modelingtable 310 and the ejection unit 200. In the embodiment, the movingmechanism 320 moves the modeling table 310 relative to the ejection unit200. The moving mechanism 320 according to the embodiment is athree-axis positioner that moves the modeling table 310 in three-axisdirections, namely the X, Y, and Z directions using drive force of threemotors. The individual motors are driven under control provided by thecontrol unit 500.

The moving mechanism 320 may have a configuration in which the ejectionunit 200 is moved without moving the modeling table 310 instead of theconfiguration in which the modeling table 310 is moved. Also, the movingmechanism 320 may have a configuration in which both the modeling table310 and the ejection unit 200 are moved. Any configuration may beemployed as long as it is possible to change the relative positions ofthe modeling table 310 and the ejection unit 200.

The control unit 500 is a computer including one or more processors, amain storage device, and an input/output interface that inputs andoutputs signals to and from the outside. In the embodiment, the controlunit 500 controls operations of the ejection unit 200 and the movingmechanism 320 and executes modeling processing of modeling athree-dimensional modeled article by a processor executing programs andcommands read on the main storage device. The operations includemovement of a three-dimensional relative positions of the ejection unit200 relative to the modeling table 310. Note that the control unit 500may be a combination of a plurality of circuits instead of the computer.

The plasticization device 90 includes a material supply unit 20 and aplasticization unit 30. The material supply unit 20 and theplasticization unit 30 communicate with each other via a supply path 22.The plasticization unit 30 and the nozzle 60 communicate with each othervia a communication hole 55. The plasticization device 90 supplies amodeling material, which is obtained in the form of a paste by meltingat least a part of a material in a solid state, to the nozzle 60.

The material supply unit 20 accommodates a material in the form ofpellets, powder, or the like. The material in the embodiment is ABSresin in the form of pellets. The material supply unit 20 in theembodiment is a hopper. The material accommodated in the material supplyunit 20 is supplied to the plasticization unit 30 via the supply path 22provided below the material supply unit 20.

The plasticization unit 30 includes a screw case 31, a drive motor 32, aflat screw 40, and a barrel 50. The screw case 31 is a case body thataccommodates the flat screw 40. The drive motor 32 is secured to anupper surface of the screw case 31. The drive motor 32 rotates the flatscrew 40 about a rotation axis RX at the center by being driven undercontrol provided by the control unit 500. Note that the flat screw 40may also simply be referred to as a screw.

In the embodiment, the flat screw 40 has a substantially columnar shape.The flat screw 40 is disposed in the screw case 31 such that therotation axis RX is in parallel to the Z direction. The drive motor 32is connected to the upper surface of the flat screw 40. The flat screw40 rotates about the rotation axis RX at the center in the screw case 31using a torque generated by the drive motor 32. The flat screw 40 has agroove formation surface 41 that is vertical to the rotation axis RX ona side opposite to the surface to which the drive motor 32 is connected.A vortex-shaped groove 45 is formed in the groove formation surface 41.Note that a detailed shape of the flat screw 40 will be described laterwith reference to FIGS. 2 to 5.

In the embodiment, the barrel 50 is secured below the screw case 31. Thebarrel 50 has a screw facing surface 51 that faces the groove formationsurface 41 of the flat screw 40. A communication hole 55 thatcommunicates with the nozzle 60 is provided in the screw facing surface51 at the position on the rotation axis RX of the flat screw 40. Aheater 58 is incorporated in the barrel 50. The temperature of theheater 58 is controlled by the control unit 500. Note that a detailedshape of the barrel 50 will be described later with reference to FIG. 6.

A nozzle flow path 62 and a nozzle hole 61 are provided in the nozzle60. The modeling material is supplied from the plasticization device 90to the nozzle flow path 62 via the communication hole 55. The modelingmaterial supplied to the nozzle flow path 62 is ejected from the nozzlehole 61. The nozzle hole 61 is a portion with a reduced flow pathsection provided at an end of the nozzle 60 on a side on which thenozzle 60 communicates with ambient air. The diameter of an opening onthe side on which the nozzle hole 61 communicates with ambient air willbe referred to as a nozzle diameter dn. A flow path sectional arearepresented as Sn=π×dn²/4 using the nozzle diameter dn and a circularconstant π will be referred to as a sectional area Sn of the nozzle hole61. The length from an end of the nozzle hole 61 on the side of theplasticization device 90 to the opening on the side on which the nozzlehole 61 communicates with the ambient air will be referred to as alength Ln of the nozzle hole 61. Note that the sectional area Sn of thenozzle hole 61 may also simply be referred to as a nozzle sectional areaSn. The length Ln of the nozzle hole 61 may simply be referred to as anozzle length Ln. In the embodiment, the diameter of the nozzle flowpath 62 is the same as the diameter of the communication hole 55. Thediameter of the nozzle flow path 62 may be smaller than that of thecommunication hole 55. The nozzle diameter do is smaller than thediameter of the nozzle flow path 62.

FIG. 2 is a perspective view illustrating a configuration of the flatscrew 40 according to the first embodiment. The flat screw 40 in FIG. 2is illustrated in a state in which the vertical positional relationshipillustrated in FIG. 1 is reversed upside down for easy understanding ofthe technology.

In the embodiment, one groove 45 is formed in the groove formationsurface 41 of the flat screw 40. The groove 45 has a central portion 46,a vortex-shaped portion 47, and a material introducing portion 48. Thecentral portion 46 is a circular concave formed around the rotation axisRX of the flat screw 40. The central portion 46 faces the communicationhole 55 provided in the barrel 50.

One end of the vortex-shaped portion 47 is connected to the centralportion 46. The vortex-shaped portion 47 extends in a vortex shape so asto draw an arc toward an outer periphery of the groove formation surface41 around the central portion 46 at the center. The vortex-shapedportion 47 may extend in an involute curve shape or a spiral shape.

The other end of the vortex-shaped portion 47 is connected to thematerial introducing portion 48. The material introducing portion 48 isa groove-shaped portion that is wider than the vortex-shaped portion 47provided at an outer peripheral edge of the screw facing surface 51. Thematerial introducing portion 48 continues up to a side surface 42 of theflat screw 40. The material supplied via the supply path 22 isintroduced from the material introducing portion 48 to the vortex-shapedportion 47.

FIG. 3 is a bottom view illustrating the groove formation surface 41 ofthe flat screw 40. In the embodiment, one end of the vortex-shapedportion 47 is connected to the central portion 46, and the other end ofthe vortex-shaped portion 47 is connected to the material introducingportion 48. A connection portion between the vortex-shaped portion andthe central portion 46 will be referred to as an outlet-side connectionportion 141, and a connection portion between the vortex-shaped portion47 and the material introducing portion 48 will be referred to as aninlet-side connection portion 142. A position at which the width of thevortex-shaped portion 47 is wider than that of the outlet-sideconnection portion 141 by 10% is assumed to be the inlet-side connectionportion 142. The length Ls of the vortex-shaped portion 47 is a lengthalong a vortex from the inlet-side connection portion 142 to theoutlet-side connection portion 141. In the embodiment, the width of thevortex-shaped portion 47 increases toward the outer periphery along thevortex. That is, the vortex-shaped portion 47 has the widest width atthe inlet-side connection portion 142 and has the narrowest width at theoutlet-side connection portion 141. Note that the length Ls of thevortex-shaped portion 47 may also be referred to as a length of thegroove 45. An arithmetic mean between a distance Rm1 from the center ofthe groove formation surface 41 to the outlet-side connection portion141 and a distance Rm2 from the center of the groove formation surface41 to the inlet-side connection portion 142 will be referred to as anaverage radius Rm=(Rm1+Rm2)/2 of the vortex-shaped portion 47.

FIG. 4 is a sectional view of the flat screw 40 taken along the lineIV-IV in FIG. 3. The section taken along the line IV-IV is a section ofthe vortex-shaped portion 47 at the outlet-side connection portion 141.In the embodiment, the shape of the section of the vortex-shaped portion47 that is vertical to a tangent direction of the vortex is a squareshape. Therefore, a sectional area Ss1 of the vortex-shaped portion 47at the outlet-side connection portion 141 can be calculated by a productof a width W1 and a depth H1 of the vortex-shaped portion 47 at theoutlet-side connection portion 141.

FIG. 5 is a sectional view of the flat screw 40 taken along the line V-Vin FIG. 3. This illustrates the section of the vortex-shaped portion 47at the inlet-side connection portion 142. In the embodiment, the shapeof the section of the vortex-shaped portion 47 that is vertical to thetangent direction of the vortex is a square shape. Therefore, asectional area Ss2 of the vortex-shaped portion at the inlet-sideconnection portion 142 can be calculated by a product of a width W2 anda depth H2 of the vortex-shaped portion 47 at the inlet-side connectionportion 142. The width W2 of the vortex-shaped portion at the inlet-sideconnection portion 142 is 1.1 times as wide as the width W1 of thevortex-shaped portion 47 at the outlet-side connection portion 141, andthe depth H2 of the vortex-shaped portion 47 at the inlet-sideconnection portion 142 is the same as the depth H1 of the vortex-shapedportion 47 at the outlet-side connection portion 141. Therefore, thesectional area Ss2 is 1.1 times as large as the sectional area Ss1.

FIG. 6 is a top view illustrating a configuration of the screw facingsurface 51 of the barrel 50 according to the first embodiment. Asdescribed above, the communication hole 55 that communicates with thenozzle hole 61 is formed at the center of the screw facing surface 51. Aplurality of guide grooves 54 are formed around the communication hole55 in the screw facing surface 51. Each of the guide grooves 54 has oneend connected to the communication hole 55 and extends in a vortex shapefrom the communication hole 55 toward the outer periphery of the screwfacing surface 51. Each of the guide grooves 54 has a function ofguiding the modeling material to the communication hole 55.

According to the aforementioned configuration of the three-dimensionalmodeling apparatus 100, the material in the material supply unit 20 issupplied from the side surface 42 of the rotating flat screw 40 to thematerial introducing portion 48 through the supply path 22 if thecontrol unit 500 executes the modeling processing of modeling athree-dimensional modeled article. The material supplied to the insideof the material introducing portion 48 is transported to the inside ofthe vortex-shaped portion by rotation of the flat screw 40. The materialtransported to the inside of the vortex-shaped portion 47 is at leastpartially melted and is turned into a modeling material in the form of apaste with fluidity through rotation of the flat screw 40 and heatingperformed by the heater 58 incorporated in the barrel 50. The modelingmaterial is transported toward the central portion 46 in thevortex-shaped portion 47 and flows into the communication hole 55 fromthe central portion 46 through rotation of the flat screw 40. Themodeling material supplied to the nozzle 60 via the communication hole55 is ejected from the nozzle hole 61 toward the modeling table 310.Note that the volumetric flow rate of the modeling material ejected fromthe nozzle hole 61 will be referred to as an amount of ejection Qout.

FIG. 7 is an explanatory diagram of a model 400 in which the groove 45of the flat screw 40 is simplified. In this model 400, a spacesurrounded by the groove 45 of the flat screw 40 and the screw facingsurface 51 of the barrel 50 is represented as a linear rectangular tube410 with a constant section. The rectangular tube 410 has the samelength as the length Ls of the vortex-shaped portion 47. The rectangulartube 410 has the same sectional area as the average sectional areaSs=(Ss1+Ss2)/2 that is an arithmetic mean between the sectional area Ss1of the vortex-shaped portion 47 at the outlet-side connection portion141 and the sectional area Ss2 of the vortex-shaped portion 47 at theinlet-side connection portion 142. The modeling material flows insidethe rectangular tube 410. Note that since the material introducingportion 48 and the central portion 46 are wider than the vortex-shapedportion 47 in this model 400, it is assumed to be ignorable. Also, theaverage sectional area Ss of the vortex-shaped portion 47 may also bereferred to as an average sectional area of the groove 45.

The rectangular tube 410 has an inlet portion 411 into which themodeling material flows and an outlet portion 412 from which themodeling material flows. In the actual ejection unit 200, the diameterof the communication hole is sufficiently larger than the nozzlediameter dn. Therefore, a nozzle portion 420 from which the modelingmaterial is ejected is connected directly to the outlet portion 412 ofthe rectangular tube 410 on the assumption that a flow path resistanceof the communication hole 55 is ignorable in the model 400. Note thatthe nozzle portion 420 has the same sectional area as that of thesectional area Sn of the nozzle. The nozzle portion 420 has the samelength as the length Ln of the nozzle. Therefore, a flow path resistancein the nozzle portion 420 is greater than a flow path resistance in therectangular tube 410.

In this model 400, relative movement between the flat screw 40 and thebarrel 50 in the actual ejection unit 200 is represented by a barrelportion 413 that corresponds to a bottom surface of the rectangular pipe410 moving from the inlet portion 411 toward the outlet portion 412 ofthe rectangular tube 410 at a constant velocity v. The velocity v is setusing an angular velocity of the rotating flat screw 40 and an averageradius Rm of the vortex-shaped portion 47.

FIGS. 8 to 10 are explanatory diagrams illustrating a flow of themodeling material in the rectangular tube 410 in the aforementionedmodel 400. FIGS. 8 to 10 illustrate distribution of the flow rate of themodeling material in the rectangular tube 410 when seen in the widthdirection of the rectangular tube 410. In this model 400, the flow ofthe modeling material is uniform in the width direction of therectangular tube 410.

FIG. 8 is a first explanatory diagram illustrating a flow of themodeling material in the rectangular tube 410. A shear flow occurs inthe modeling material in the rectangular tube 410 by the barrel portion413 moving at the velocity v. The modeling material is transported inthe rectangular tube 410 from the inlet portion 411 toward the outletportion 412 due to the shear flow. The flow rate of the modelingmaterial transported from the inlet portion 411 toward the outletportion 412 in the rectangular tube 410 will be referred to as an amountof transport Qin.

FIG. 9 is a second explanatory diagram illustrating a flow of themodeling material in the rectangular tube 410. Since the flow pathresistance of the nozzle portion 420 is greater than the flow pathresistance in the rectangular tube 410, a back pressure that is apressure of the modeling material at the outlet portion 412 in therectangular tube 410 rises as the modeling material is transported inthe rectangular tube 410. A part of the modeling material transported isrefluxed in the rectangular tube 410 from the side of the outlet portion412 toward the side of the inlet portion 411 due to a differentialpressure ΔP generated between the inlet portion 411 and the outletportion 412 due to a rise in back pressure. The flow rate of themodeling material refluxed in the rectangular pipe 410 will be referredto as an amount of reflux Qrev.

FIG. 10 is a third explanatory diagram illustrating a flow of themodeling material in the rectangular tube 410. If the back pressurefurther rises, the amount of reflux Qrev in the rectangular tube 410increases since the differential pressure ΔP between the inlet portion411 and the outlet portion 412 further increases.

Therefore, it is not possible to obtain a sufficient amount of ejectionQout if the amount of reflux Qrev excessively increases. Therefore, theamount of reflux Qrev and the amount of ejection Qout are preferablyequal to each other in order to increase the amount of ejection Qout.

Both the pressure at the inlet portion 411 in the rectangular pipe 410and the pressure at an end of the nozzle portion 420 on the sideopposite to the rectangular pipe 410 are an ambient pressure. Therefore,a relationship between a pressure loss at the rectangular tube 410 and apressure loss at the nozzle portion 420 are represented as Formula (1)below:{128×μ(γrev)×Ls/π×ds ⁴ }×Qrev={128×μ(γin)×Ln/π×dn ⁴ }×Qout  (1)

In Formula (1) described above, μ(γrev) represents a shear velocitydependent velocity for the modeling material refluxed in the rectangulartube 410. Ls represents a length of the rectangular tube 410. dsrepresents a diameter of a circular tube with a sectional area that isequivalent to the sectional area Ss of the rectangular tube 410. μ(γin)represents a shear velocity depending viscosity of the modeling materialejected from the nozzle portion 420. Ln represents a length of thenozzle portion 420. dn represents a diameter of a circular tube with asectional area that is equivalent to the sectional area Sn of the nozzleportion 420. Note that in the following description, the amount oftransport Qin, the amount of reflux Qrev, and the amount of ejectionQout will simply be referred to as Q by omitting the subscripts whendescription is given without particularly distinguishing these amounts.The average shear velocity γin of the modeling material transported inthe rectangular tube 410 and the average shear velocity yrev of themodeling material refluxed in the rectangular tube 410 will simply bereferred to as γ by omitting the subscripts when description is givenwithout particularly distinguishing these velocities. The sectional areaSs of the rectangular tube 410 and the sectional area Sn of the nozzleportion 420 will simply be referred to as S by omitting the subscriptswhen description is given without particularly distinguishing thesesectional areas.

The shear velocity dependent viscosity μ(γ) is represented as Formula(2) below using a viscosity μ0 of the modeling material on theassumption of a Newtonian fluid that does not depend on the shearvelocity, a shear stress τ acting on the modeling material, and theaverage shear velocity y of the modeling material.μ(γ)=μ0/(1+(τ×γ)^(α)  (2)

The sectional area Ss of the rectangular tube 410 is represented asFormula (3) below using the diameter ds of the circular tube with asectional area that is equivalent to the sectional area Ss of therectangular tube 410.π×ds ²/4=Ss  (3)

The sectional area Sn of the nozzle portion 420 is represented asFormula (4) below using the diameter do of the circular tube with asectional area that is equivalent to the sectional area Sn of the nozzleportion 420.π×dn ²/4=Sn  (4)

The fact that the amount of reflux Qrev in the rectangular pipe 410 isthe same as the amount of ejection Qout from the nozzle portion 420 isrepresented as Formula (5) below.Qrev=Qout  (5)

From Formula (1) described above, the relationship of Formula (6) belowis required to be established in order for the amount of reflux Qrev inthe rectangular pipe 410 and the amount of ejection Qout from the nozzleportion 420 to be the same.{μ(γrev)×Ls/Ss}={μ(γin)×Ln/Sn}  (6)

Since the flat screw 40 is used in a high-shear region, the shearvelocity dependent velocity μ(γ) can be approximated as Formula (7)below using a viscosity μ0 of the modeling material on the assumption ofa Newtonian fluid that does not depend on the shear velocity, the shearstress τ, and the shear velocity γ. Note that the value of α is about0.6 to about 0.8 in a case of molten resin, the shear velocity dependentviscosity μ(γ) can be approximated to ⅔.μ(γ)=μ0/(τ×γ)^(α)  (7)

Also, the average shear velocity y is represented as Formula (8) belowusing the flow rate Q and the sectional area Sγ=Q/S ^(3/2)  (8)

If Formula (6) described above is arranged using Formulae (5), (7), and(8) described above, the relationship represented as Formula (9) belowis extracted.Ss/Ls=Sn/Ln  (9)

Therefore, it is considered that the amount of ejection Qout increaseswhen the value (Ss/Ls)/(Sn/Ln) becomes about 1.00. That is, it isconsidered that the amount of ejection of the modeling material from thenozzle hole 61 increases by setting the average sectional area Ss andthe length Ls of the vortex-shaped portion 47 and the sectional area Snand the length Ln of the nozzle hole 61 such that the value of(Ss/Ls)/(Sn/Ln) becomes about 1.00. Note that (Ss/Ls)/(Sn/Ln) will bereferred to as an S/L ratio below. The ratio Sn/Ln of the sectional areaSn of the nozzle hole 61 with respect to the length Ln of the nozzlehole 61 will be referred to as a nozzle ratio. The ratio Ss/Ls of theaverage sectional area Ss of the vortex-shaped portion 47 with respectto the length Ls of the vortex-shaped portion 47 will be referred to asa groove ratio. That is, the S/L ratio means a ratio of the groove ratioSs/Ls with respect to the nozzle ratio Sn/Ln.

FIGS. 11, 13, 15, and 17 are graphs illustrating relationships betweenthe S/L ratio and the amount of ejection. In FIGS. 11, 13, 15, and 17,the horizontal axis represents the S/L ratio, and the vertical axisrepresents the amount of ejection of the modeling material from thenozzle hole 61. The amount of ejection illustrated in FIGS. 11, 13, 15,and 17 is represented as a proportion with reference to the amount ofejection when the S/L ratio in FIG. 11 is 4.58. Note that it isconsidered that the S/L ratio is set to about 20.00 in thethree-dimensional modeling apparatus in the related art. Hereinafter,results of an experiment performed to confirm that the amount ofejection increases when the value of the S/L ratio is about 1.00 will bedescribed with reference to FIGS. 11, 13, 15, and 17. In thisexperiment, a relationship between the S/L ratio and the amount ofejection was examined by changing the average sectional area Ss of thevortex-shaped portion 47 within a range of 6.25×10⁻⁸ to 3.60×10⁻³ m².

FIG. 11 is a first graph illustrating the relationship between the S/Lratio and the amount of ejection. In the experiment whose results areillustrated in FIG. 11, a nozzle 60 with a nozzle diameter dn=50 μm anda nozzle length Ln=200 μm was used. ABS resin was used as a material.The temperature of the heater 58 was set such that the temperature ofthe material became 200.0 degrees Celsius. The rotation frequency of theflat screw 40 was set to 60 rpm. The flat screw 40 with an averageradius Rm of the vortex-shaped portion 47=16 mm and the length Ls of thevortex-shaped portion 47=200 mm was used. Note that illustration of acase in which the S/L ratio is equal to or greater than 5.00 is omittedin FIG. 11.

FIG. 12 is a first table illustrating a relationship of the averagesectional area Ss, the S/L ratio, and the amount of ejection. FIG. 12represents a relationship of the average sectional area Ss of thevortex-shaped portion 47, the S/L ratio, and the amount of ejection fromthe nozzle hole 61 at the position indicated with a circle mark in FIG.11. Note that although illustration of the case in which the S/L ratiois equal to or greater than 5.00 is omitted in FIG. 11, the case inwhich the S/L ratio is equal to or greater than 5.00 is also illustratedin FIG. 12. When the S/L ratio is 18.33, the amount of ejection is 11%.When the S/L ratio is 12.73, the amount of ejection is 20%. When the S/Lratio is 8.15, the amount of ejection is 40%. When the S/L ratio is6.24, the amount of ejection is 50%. When the S/L ratio is 4.58, theamount of ejection is 100%. When the S/L ratio is 3.18, the amount ofejection is 167%. When the S/L ratio is 2.04, the amount of ejection is333%. When the S/L ratio is 1.15, the amount of ejection is 767%. Whenthe S/L ratio is 0.51, the amount of ejection is 1577%. When the S/Lratio is 0.29, the amount of ejection is 1587%. When the S/L ratio is0.13, the amount of ejection is 1000%. When the S/L ratio is 0.03, theamount of ejection is 320%.

As a result of the aforementioned experiment, it was found that theupper limit and the lower limit of the S/L ratio were preferably set asfollows in order to increase the amount of ejection from the nozzle hole61. It was found that the upper limit of the S/L ratio was preferablyequal to or less than 5.00, was more preferably equal to or less than2.00, and was further preferably equal to or less than 1.00. It wasfound that the lower limit of the S/L ratio was preferably equal to orgreater than 0.03, was more preferably equal to or greater than 0.10,and was further preferably equal to or greater than 0.20.

FIG. 13 is a second graph illustrating a relationship between an S/Lratio and an amount of ejection. In an experiment whose result isillustrated in FIG. 13, a nozzle 60 with a nozzle diameter dn=50 μm andwith a nozzle length Ln=200 μm was used. As a material, polypropylene(PP) was used. The temperature of the heater 58 was set such that thetemperature of the material became 200.0 degrees Celsius. The rotationfrequency of the flat screw 40 is set to 60 rpm. The flat screw 40 withan average radius Rm of the vortex-shaped portion 47=16 mm and thelength Ls of the vortex-shaped portion 47=200 mm was used.

FIG. 14 is a second table illustrating a relationship between an averagesectional area Ss, an S/L ratio, and an amount of ejection. FIG. 14illustrates a relationship between the average sectional area Ss of thevortex-shaped portion 47, the S/L ratio, and the amount of ejection fromthe nozzle hole 61 at a position indicated with the circle mark in FIG.13. When the S/L ratio is 18.33, the amount of ejection is 5%. When theS/L ratio is 12.73, the amount of ejection is 12%. When the S/L ratio is8.15, the amount of ejection is 29%. When the S/L ratio is 6.24, theamount of ejection is 43%. When the S/L ratio is 4.58, the amount ofejection is 123%. When the S/L ratio is 3.18, the amount of ejection is263%. When the S/L ratio is 2.04, the amount of ejection is 499%. Whenthe S/L ratio is 1.15, the amount of ejection is 833%. When the S/Lratio is 0.51, the amount of ejection is 1377%. When the S/L ratio is0.29, the amount of ejection is 1533%. When the S/L ratio is 0.13, theamount of ejection is 1100%. When the S/L ratio is 0.03, the amount ofejection is 337%.

As a result of the aforementioned experiment, it was found that theupper limit and the lower limit of the S/L ratio were preferably set asfollows in order to increase the amount of ejection from the nozzle hole61. It was found that the upper limit of the S/L ratio was preferablyequal to or less than 5.00, was more preferably equal to or less than2.00, and was further preferably equal to or less than 1.00. It wasfound that the lower limit of the S/L ratio was preferably equal to orgreater than 0.03, was more preferably equal to or greater than 0.10,and was further preferably equal to or greater than 0.20.

FIG. 15 is a third graph illustrating a relationship of an S/L ratio andan amount of ejection. In the experiment whose result is illustrated inFIG. 15, a nozzle 60 with a nozzle diameter dn=100 μm and a nozzlelength Ln=200 μm was used. ABS resin was used as a material. Thetemperature of the heater 58 was set such that the temperature of thematerial became 200.0 degrees Celsius. The rotation frequency of theflat screw 40 was set to 60 rpm. The flat screw 40 with an averageradius Rm of the vortex-shaped portion 47=16 mm and a length Ls of thevortex-shaped portion 47=200 mm was used. Note that illustration of acase in which the S/L ratio is equal to or greater than 5.00 is omittedin FIG. 15.

FIG. 16 is a third table illustrating a relationship of an averagesectional area Ss, an S/L ratio, and an amount of ejection. FIG. 16illustrates a relationship of the average sectional area Ss of thevortex-shaped portion 47, the S/L ratio, and the amount of ejection fromthe nozzle hole 61 at the position indicated with the circle mark inFIG. 15. Note that although illustration of the case in which the S/Lratio is equal to or greater than 5.00 is omitted in FIG. 15, the casein which the S/L ratio is equal to or greater than 5.00 is alsoillustrated in FIG. 16. When the S/L ratio is 4.58, the amount ofejection is 267%. When the S/L ratio is 3.18, the amount of ejection is500%. When the S/L ratio is 2.04, the amount of ejection is 1033%. Whenthe S/L ratio is 1.56, the amount of ejection is 1600%. When the S/Lratio is 1.15, the amount of ejection is 2433%. When the S/L ratio is0.80, the amount of ejection is 3800%. When the S/L ratio is 0.51, theamount of ejection is 5667%. When the S/L ratio is 0.29, the amount ofejection is 6233%. When the S/L ratio is 0.13, the amount of ejection is4000%. When the S/L ratio is 0.07, the amount of ejection is 2567%. Whenthe S/L ratio is 0.03, the amount of ejection is 1267%. When the S/Lratio is 0.01, the amount of ejection is 333%.

As a result of the aforementioned experiment, it was found that theupper limit and the lower limit of the S/L ratio were preferably set asfollows in order to increase the amount of ejection from the nozzle hole61. It was found that the upper limit of the S/L ratio was preferablyequal to or less than 5.00, was more preferably equal to or less than2.00, and was further preferably equal to or less than 1.00. It wasfound that the lower limit of the S/L ratio was equal to or greater than0.03, was more preferably equal to or greater than 0.10, and was furtherpreferably equal to or greater than 0.20.

FIG. 17 is a fourth graph illustrating a relationship of an S/L ratioand an amount of ejection. In the experiment whose result is illustratedin FIG. 17, a nozzle 60 with a nozzle diameter dn=200 μm and a nozzlelength Ln=1000 μm was used. ABS resin was used as a material. Thetemperature of the heater 58 was set such that the temperature of thematerial became 200.0 degrees Celsius. The rotation frequency of theflat screw 40 was set to 60 rpm. The flat screw 40 with an averageradius Rm of the vortex-shaped portion 47=16 mm and a length Ls of thevortex-shaped portion 47=200 mm was used. Note that illustration of acase in which the S/L ratio is equal to or greater than 5.00 is omittedin FIG. 17.

FIG. 18 is a fourth table illustrating a relationship of an averagesectional area Ss, an S/L ratio, and an amount of ejection. FIG. 18illustrates a relationship of the average sectional area Ss of thevortex-shaped portion 47, the S/L ratio, and the amount of ejection fromthe nozzle hole 61 at the position indicated by the circle mark in FIG.17. Although the case in which the S/L ratio is equal to or greater than5.00 is omitted in FIG. 17, the case in which the S/L ratio is equal toor greater than 5.00 is also illustrated in FIG. 18. When the S/L ratiois 5.73, the amount of ejection is 333%. When the S/L ratio is 3.98, theamount of ejection is 667%. When the S/L ratio is 2.55, the amount ofejection is 1400%. When the S/L ratio is 1.95, the amount of ejection is2200%. When the S/L ratio is 1.43, the amount of ejection is 3533%. Whenthe S/L ratio is 0.99, the amount of ejection is 5800%. When the S/Lratio is 0.64, the amount of ejection is 7000%. When the S/L ratio is0.36, the amount of ejection is 7000%. When the S/L ratio is 0.16, theamount of ejection is 4167%. When the S/L ratio is 0.09, the amount ofejection is 2633%. When the S/L ratio is 0.04, the amount of ejection is1000%.

When the S/L ratio is 0.01, the amount of ejection is 333%.

As a result of the aforementioned experiment, it was found that theupper limit and the lower limit of the S/L ratio were preferably set asfollows in order to increase the amount of ejection from the nozzle hole61. It was found that the upper limit of the S/L ratio was preferablyequal to or less than 5.00, is more preferably equal to or less than2.50, and is further preferably equal to or less than 1.50. It was foundthat the lower limit of the S/L ratio was preferably equal to or greaterthan 0.04, was more preferably equal to or greater than 0.10, and wasfurther preferably equal to or greater than 0.15.

FIG. 19 is a graph illustrating shear velocity dependency of a viscosityof the ABS resin used in the aforementioned experiment. In FIG. 19, thehorizontal axis represents a shear velocity, and the vertical axisrepresents a viscosity. In FIG. 19, relationships between the shearvelocity and the viscosity at 180.0 degrees Celsius, 200.0 degreesCelsius, 220.0 degrees Celsius, 240.0 degrees Celsius, and 260.0 degreesCelsius are illustrated using a double-logarithmic graph.

FIG. 20 is a graph illustrating shear velocity dependency of a viscosityof polypropylene used in the aforementioned experiment. In FIG. 20, thehorizontal axis represents a shear velocity, and the vertical axisrepresents a viscosity. In FIG. 20, relationships between the shearvelocity and the viscosity at 180.0 degrees Celsius, 206.7 degreesCelsius, 233.3 degrees Celsius, and 260.0 degrees Celsius areillustrated using a double-logarithmic graph.

According to the three-dimensional modeling apparatus 100 in theembodiment as described above, it is possible to increase the amount ofejection of the modeling material from the nozzle hole 61 by setting theaverage sectional area Ss and the length Ls of the vortex-shaped portion47 of the flat screw 40 and the sectional area Sn and the length Ln ofthe nozzle hole 61 such that the S/L ratio falls within a range of equalto or greater than 0.03 and equal to or less than 5.00. In particular,it is possible to further increase the amount of ejection of themodeling material from the nozzle hole 61 when the S/L ratio fallswithin a range of equal to or greater than 0.03 and equal to or lessthan 2.00 in the embodiment.

In the embodiment, it is possible to significantly increase the amountof ejection of the modeling material from the nozzle hole 61 by settingthe average sectional area Ss and the length Ls of the vortex-shapedportion 47 of the flat screw 40 and the sectional area Sn and the lengthLn of the nozzle hole 61 such that the S/L ratio falls within a range ofequal to or greater than 0.10 and equal to or less than 1.00.

In the embodiment, it is still possible to prevent the amount ofejection of the modeling material from the nozzle hole 61 from beingreduced by appropriately setting the S/L ratio even in a case of asmall-diameter nozzle 60 with a nozzle diameter do of equal to or lessthan 200 μm.

Since the vortex-shaped portion 47 becomes narrower from the materialintroducing portion 48 toward the central portion 46, it is possible toeffectively melt and transport the material in the vortex-shaped portion47 in the embodiment.

B. Second Embodiment

FIG. 21 is a bottom view illustrating a groove formation surface 41 of aflat screw 40 b in a three-dimensional modeling apparatus 100 baccording to a second embodiment. The three-dimensional modelingapparatus 100 b according to the second embodiment is different from thefirst embodiment in that two grooves 45 are formed in the grooveformation surface 41 of the flat screw 40 b. The other configurationsare the same as those in the first embodiment illustrated in FIG. 1unless otherwise particularly indicated.

In the embodiment, the sectional area Ss1 of the outlet-side connectionportion 141 of the vortex-shaped portion 47 is the same as the sectionalarea Ss2 of the inlet-side connection portion 142 at each of the grooves45. The length Ls of the vortex-shaped portion 47 is the same at each ofthe grooves 45.

The fact that the amount of reflux Qrev in the rectangular tube 410 isthe same as the amount of ejection Qout from the nozzle portion 420 whena plurality of grooves 45 are provided is represented as Formula (10)below using the number n of the grooves 45. Note that n is a naturalnumber.n×Qrev=Qout  (10)

Therefore, a relationship represented as Formula (11) below is extractedusing Formulae (1) to (4) and Formulae (6) to (8) described above.n ^(1/2) ×Ss/Ls=Sn/Ln  (11)

Therefore, it is considered that the amount of ejection increases whenn^(1/2)×(Ss/Ls)/(Sn/Ln) is a value around 1.00 when a plurality ofgrooves 45 are provided. That is, it is considered that the amount ofejection increases when the S/L ratio is a value around 0.71 in theconfiguration in which two grooves 45 are provided, and that the amountof ejection increases when the S/L ratio is a value about 0.58 in theconfiguration in which three grooves 45 are provided. Note thatn^(1/2)×(Ss/Ls)/(Sn/Ln) will be referred to as an amended S/L ratiobelow.

FIG. 22 is a graph illustrating a relationship between an S/L ratio andan amount of ejection when a plurality of grooves 45 are provided. InFIG. 22, the horizontal axis represents an S/L ratio, and the verticalaxis represents the amount of ejection of the modeling material from thenozzle hole 61. The amount of ejection illustrated in FIG. 22 isrepresented as a proportion with reference to the amount of ejectionwhen the S/L ratio is 4.58 when one groove 45 is provided. FIG. 22illustrates a result of an experiment conducted in order to confirm thatthe amount of ejection increases when the S/L ratio is a value around0.71 in the configuration in which two grooves 45 are provided and theamount of ejection increases when the S/L ratio is a value around 0.58in the configuration in which three grooves 45 are provided.

In the experiment whose result is illustrated in FIG. 22, a nozzle 60with a nozzle diameter dn=50 μm and a nozzle length Ln=200 μm was usedin each of a case in which one groove 45 was provided, a case in whichtwo grooves 45 were provided, and a case in which three grooves 45 wereprovided. ABS resin was used as a material. The temperature of theheater 58 was set such that the temperature of the material became 200.0degrees Celsius. The rotation frequency of the flat screw 40 was set to60 rpm. A flat screw 40 b with an average radius Rm of the vortex-shapedportion 47=16 mm and a length Ls of the vortex-shaped portion 47=200 mmwas used. Note that illustration of a case in which the S/L ratio isequal to or greater than 5.00 is omitted in FIG. 22. Results of the casein which one groove 45 was provided are the same as the resultsdescribed above with reference to FIGS. 11 and 12.

FIG. 23 is a table illustrating a relationship of an average sectionalarea Ss, an S/L ratio, and an ejection amount when two grooves 45 areprovided. FIG. 23 illustrates a relationship of the average sectionalarea Ss of the vortex-shaped portion 47, the S/L ratio, and the amountof ejection from the nozzle hole 61 at the position indicated by thecircle mark in FIG. 22. When the S/L ratio is 18.33, the amount ofejection is 9%. When the S/L ratio is 12.73, the amount of ejection is18%. When the S/L ratio is 8.15, the amount of ejection is 39%. When theS/L ratio is 6.24, the amount of ejection is 65%. When the S/L ratio is4.58, the amount of ejection is 102%. When the S/L ratio is 3.18, theamount of ejection is 186%. When the S/L ratio is 2.04, the amount ofejection is 357%. When the S/L ratio is 1.15, the amount of ejection is770%. When the S/L ratio is 0.51, the amount of ejection is 1720%. Whenthe S/L ratio is 0.29, the amount of ejection is 2340%. When the S/Lratio is 0.13, the amount of ejection is 1780%. When the S/L ratio is0.03, the amount of ejection is 550%.

FIG. 24 is a table illustrating a relationship of an average sectionalarea Ss, an S/L ratio, and an amount of ejection when three grooves 45are provided. FIG. 24 illustrates a relationship of the averagesectional area Ss of the vortex-shaped portion 47, the S/L ratio, andthe amount of ejection from the nozzle hole 61 at the position indicatedby the circle mark in FIG. 22. When the S/L ratio is 18.33, the amountof ejection is 9%. When the S/L ratio is 12.73, the amount of ejectionis 18%. When the S/L ratio is 8.15, the amount of ejection is 39%. Whenthe S/L ratio is 6.24, the amount of ejection is 64%. When the S/L ratiois 4.58, the amount of ejection is 102%. When the S/L ratio is 3.18, theamount of ejection is 187%. When the S/L ratio is 2.04, the amount ofejection is 357%. When the S/L ratio is 1.15, the amount of ejection is790%. When the S/L ratio is 0.51, the amount of ejection is 1893%. Whenthe S/L ratio is 0.29, the amount of ejection is 2813%. When the S/Lratio is 0.13, the amount of ejection is 2340%. When the S/L ratio is0.03, the amount of ejection is 853%.

As a result of the aforementioned experiment, a peak position of theamount of ejection appears on a side on which the S/L ratio is smallerwhen two grooves 45 are provided than when one groove 45 is provided.Further, a peak position of the amount of ejection appears on a side onwhich the S/L ratio is smaller when three grooves 45 are provided thanwhen two grooves 45 are provided.

According to the three-dimensional modeling apparatus 100 b in theembodiment as described above, it is possible to increase the amount ofejection of the modeling material from the nozzle hole 61 by setting theaverage sectional Ss and the length Ls of the vortex-shaped portion 47of the flat screw 40 and the sectional area Sn and the length Ln of thenozzle hole 61 such that the amended S/L ratio falls within a range ofequal to or greater than 0.03 and equal to or less than 5.00 even when aplurality of grooves 45 are provided. In particular, it is possible tofurther increase the amount of ejection of the modeling material fromthe nozzle hole 61 when the amended S/L ratio falls within a range ofequal to or greater than 0.03 and equal to or less than 2.00 in theembodiment.

According to the embodiment, it is possible to significantly increasethe amount of ejection of the modeling material from the nozzle hole 61by setting the average sectional area Ss and the length Ls of thevortex-shaped portion 47 of the flat screw 40 and the sectional area Snand the length Ln of the nozzle hole 61 such that the amended S/L ratiofalls within a range of equal to or greater than 0.10 and equal to orless than 1.00 even when a plurality of grooves 45 are provided.

C. Other embodiments

(C1) In the three-dimensional modeling apparatuses 100 and 100 b in theaforementioned respective embodiments, a plurality of ejection units 200may be provided. In this case, the modeling material can be ejected fromthe ejection units 200.

(C2) In the three-dimensional modeling apparatuses 100 and 100 b in theaforementioned respective embodiments, a plurality of communicationholes 55 may be provided in the screw facing surface 51 of the barrel50. In this case, the modeling material can be ejected from a pluralityof nozzles 60.

(C3) FIG. 25 is an explanatory diagram illustrating an outlineconfiguration of an injection molding apparatus 110 according to anotherembodiment. The ejection units 200 and 200 b may be used in theinjection molding apparatus 110 as well as the three-dimensionalmodeling apparatuses 100 and 100 b. In the injection molding apparatus110 illustrated in FIG. 25, the ejection unit 200 includes an injectionunit 600 in addition to the plasticization device 90 and the nozzle 60.The configuration and the functions of the plasticization device 90 areas described above. Note that illustration of the material supply unit20 and the supply path 22 is omitted in FIG. 25. The injection unit 600weights out a molten material supplied from the plasticization device 90and injects the molten material from the nozzle 60 to a space sectionedby an upper mold 710 and a lower mold, which is not illustrated in thedrawing, in a clamped state. The injection unit 600 has an injectioncylinder 610, an injection plunger 620, a check valve 630, and aninjection motor 640. The molten material in the communication hole 55 isdrawn into the injection cylinder 610 and is then weighed out therein bythe injection plunger 620 sliding on a side opposite to the side of thecommunication hole 55 due to drive of the injection motor 640. Themolten material in the injection cylinder 610 is pressure-fed to theside of the nozzle 60 and is then injected to the space sectioned by theupper mold 710 and the lower mold by the injection plunger 620 slidingon the side of the communication hole 55 due to drive of the injectionmotor 640.

D. Other Modes

The present disclosure is not limited to the aforementioned embodimentsand can be realized in various modes without departing from the gistthereof. For example, the present disclosure can also be realized in thefollowing modes. The technical features in the aforementionedembodiments corresponding to technical features in the respective modesdescribed below can appropriately be replaced or combined in order tosolve a part of or entire problems of the present disclosure or toachieve a part of or entire effects of the present disclosure. Also,some technical features can appropriately be eliminated as long as thereis no description that the technical features are essential in thespecification.

(1) According to a mode of the present disclosure, there is provided athree-dimensional modeling apparatus. The three-dimensional modelingapparatus includes: a drive motor; a screw that has a groove formationsurface with a groove formed therein and that is rotated by the drivemotor; a barrel that faces the groove formation surface and has a facingsurface with a communication hole formed at the center thereof and aheater; and a nozzle that ejects a modeling material supplied from thecommunication hole. A relationship of an average sectional area Ss thatis an arithmetic mean between a maximum sectional area and a minimumsectional area of the groove, a length Ls of the groove, a sectionalarea Sn of the nozzle, and a length Ln of the nozzle satisfies Formula(1) below.0.03≤(Ss/Ls)/(Sn/Ln)≤5.00  (1).

According to the three-dimensional modeling apparatus in this mode, itis possible to increase the amount of ejection of the modeling materialfrom the nozzle by setting the dimension of the groove of the screw andthe dimension of the nozzle such that the value of (Ss/Ls)/(Sn/Ln) fallswithin a range of equal to or greater than 0.03 and equal to or lessthan 5.00.

(2) In the three-dimensional modeling apparatus in the aforementionedmode, the relationship may satisfy Formula (2) below.0.03≤(Ss/Ls)/(Sn/Ln)≤2.00  (2)

According to the three-dimensional modeling apparatus in theaforementioned mode, it is possible to further increase the amount ofejection of the modeling material from the nozzle by setting thedimension of the groove of the screw and the dimension of the nozzlesuch that the value of (Ss/Ls)/(Sn/Ln) falls within a range of equal toor greater than 0.03 and equal to or less than 2.00.

(3) In the three-dimensional modeling apparatus in the aforementionedmode, the relationship may satisfy Formula (3) below.0.10≤(Ss/Ls)/(Sn/Ln)≤1.00  (3)

According to the three-dimensional modeling apparatus in this mode, itis possible to significantly increase the amount of ejection of themodeling material from the nozzle by setting the dimension of the grooveof the screw and the dimension of the nozzle such that the value of(Ss/Ls)/(Sn/Ln) falls within the range of equal to or greater than 0.10and equal to or less than 1.00.

(4) In the three-dimensional modeling apparatus in the aforementionedmode, a diameter of the nozzle may be equal to or less than 200 μm.

According to the three-dimensional modeling apparatus in the mode, it ispossible to prevent the amount of ejection of the modeling material fromthe nozzle from being reduced by appropriately setting the value of(Ss/Ls)/(Sn/Ln) even if the diameter of the nozzle is equal to or lessthan 200 μm.

(5) In the three-dimensional modeling apparatus according to theaforementioned mode, a sectional area of the groove decreases toward thecommunication hole.

According to the three-dimensional modeling apparatus in this mode, itis possible to effectively melt and transport the material in the grooveof the screw.

(6) According to a second mode of the present disclosure, there isprovided a three-dimensional modeling apparatus. The three-dimensionalmodeling apparatus includes: a drive motor; a screw that has a grooveformation surface with n grooves formed therein and that is rotated bythe drive motor; a barrel that has a facing surface facing the grooveformation surface and having a communication hole formed at the centerthereof and a heater; and a nozzle that ejects a modeling materialsupplied from the communication hole. The n grooves are connected toeach other at end portions at a center side of a vortex, and arelationship among an average sectional area Ss that is an arithmeticmean between a maximum sectional area and a minimum sectional area ofeach of the n grooves, a length Ls of the grooves, a sectional area Snof the nozzle, a length Ln of the nozzle, and the number n of thegrooves satisfy Formula (4) below.0.03≤n ^(1/2)×(Ss/Ls)/(Sn/Ln)≤5.00  (4)where n is a natural number

According to the three-dimensional modeling apparatus in this mode, itis possible to increase the amount of ejection of the modeling materialfrom the nozzle by setting the dimension of the groove of the screw andthe dimension of the nozzle such that the value ofn^(1/2)×(Ss/Ls)/(Sn/Ln) falls within a range of equal to or greater than0.03 and equal to or less than 5.00.

(7) According to a third mode of the present disclosure, there isprovided an ejection unit. The ejection unit includes: a drive motor; ascrew that has a groove formation surface with a groove formed thereinand that is rotated by the drive motor; a barrel that has a facingsurface facing the groove formation surface and having a communicationhole formed at the center thereof and a heater; and a nozzle that ejectsa modeling material supplied from the communication hole. A relationshipamong an average sectional area Ss that is an arithmetic mean between amaximum sectional area and a minimum sectional area of the groove, alength Ls of the groove, a sectional area Sn of the nozzle, and a lengthLn of the nozzle satisfies Formula (5) below.0.03≤(Ss/Ls)/(Sn/Ln)≤5.00  (5)

According to the ejection unit in this mode, it is possible to increasethe amount of ejection of the modeling material from the nozzle bysetting the dimension of the groove of the screw and the dimension ofthe nozzle such that the value of (Ss/Ls)/(Sn/Ln) falls within a rangeof equal to or greater than 0.03 and equal to or less than 5.00.

The present disclosure can also be realized in various modes other thanthe three-dimensional modeling apparatus. For example, the presentdisclosure can be realized in modes such as an ejection unit and aninjection molding apparatus.

What is claimed is:
 1. A three-dimensional modeling apparatuscomprising: a drive motor; a screw that has a groove formation surfacein which a spiral groove and a spiral wall are formed, the screw beingrotated by the drive motor, the spiral groove being formed betweenadjacent outer sides of the spiral wall; a barrel that has a facingsurface facing the groove formation surface, the barrel having acommunication hole that is formed at a center of the facing surface, thebarrel having a heater; wherein the spiral groove includes a centralportion, a vortex-shaped portion, and a material introducing portion,the central portion faces the communication hole; a nozzle that isconfigured to eject a modeling material supplied via the communicationhole; a modeling table facing the nozzle and receiving the modelingmaterial from the nozzle, a tip of the nozzle and the modeling tablebeing spaced apart from each other; and a moving mechanism disposedbelow the modeling table, the moving mechanism being configured to movethe table toward the nozzle or away from the nozzle, wherein a width ofthe spiral groove of the screw is smaller than a width of the ridge ofthe screw, and Ss is an average sectional area that is an arithmeticmean between a maximum sectional area and a minimum sectional area ofthe spiral groove, Ls is a length of the spiral groove, Sn is asectional area of the nozzle, Ln is a length of the nozzle, and0.03<(Ss/Ls)/(Sn/Ln)<5.00.
 2. The three-dimensional modeling apparatusaccording to claim 1, wherein0.03≤(Ss/Ls)/(Sn/Ln)≤2.00.
 3. The three-dimensional modeling apparatusaccording to claim 1, wherein0.10≤(Ss/Ls)/(Sn/Ln)≤1.00.
 4. The three-dimensional modeling apparatusaccording to claim 1, wherein a diameter of the nozzle is equal to orless than 200 μm.
 5. The three-dimensional modeling apparatus accordingto claim 1, wherein a sectional area of the spiral groove decreasestoward the communication hole.
 6. A three-dimensional modeling apparatuscomprising: a drive motor; a screw that has a groove formation surfacein which n spiral grooves and n spiral walls are formed, the screw beingrotated by the drive motor, the n spiral grooves being formed betweenadjacent outer sides of the n spiral walls, the n being a natural numberof two or more; a barrel that has a facing surface facing the grooveformation surface, the barrel having a communication hole that is formedat a center of the facing surface, the barrel having a heater; whereinthe groove includes a central portion, a vortex-shaped portion, and amaterial introducing portion, the central portion faces thecommunication hole; a nozzle that is configured to eject a modelingmaterial supplied via the communication hole; a modeling table facingthe nozzle and receiving the modeling material from the nozzle, a tip ofthe nozzle and the modeling table being spaced apart from each other;and a moving mechanism disposed below the modeling table, the movingmechanism being configured to move the table toward the nozzle or awayfrom the nozzle, wherein ends of the n spiral grooves are connected toeach other at a center area of the groove formation surface, a width ofeach of the n spiral grooves of the screw is smaller than a width of theridge of the screw, and Ss is an average sectional area that is anarithmetic mean between a maximum sectional area and a minimum sectionalarea of each of the n spiral grooves, Ls is a length of each of the nspiral grooves, Sn is a sectional area of the nozzle, Ln is a length ofthe nozzle, and 0.03≤n½×(Ss/Ls)/(Sn/Ln)<5.00.